This invention relates in general to knives, and more particularly to a knife which is particularly suited for slitting sheet material, such as corrugated paperboard.
Many of the goods sold in this country are shipped in boxes constructed from paperboard, usually corrugated paperboard, and this not only holds true with regard to individually packaged items, but bulk items as well. Indeed, employees of retail stores spend considerable time merely opening corrugated paperboard boxes and unpacking the contents for display in such stores. Special box knives exist for this purpose.
The typical box knife consists of nothing more than a handle which contains a retractable blade holder or carrier, and the blade carrier, as its name implies, holds a blade. When the carrier is extended it projects the blade beyond the end of the handle where its cutting edge is exposed more or less as an extension of the lower surface of the handle. To use the knife to open a corrugated paperboard box, one merely grasps the knife handle and runs the cutting edge of the blade along walls of the box, urging the handle inwardly with enough force to enable the blade to penetrate and actually slit the box.
While the blade of the typical box knife retracts, users on many occasions do not make the effort to retract it prior to setting the knife aside, so the knife with its exposed cutting edge presents a danger to those who may come against it. An even greater danger exists when the knife is in use, for its blade must be forced along the wall of the box against appreciable resistance, but once the blade clears the end of the box, the resistance terminates, and if the user does not exercise caution, the knife with its exposed blade could cut the user or someone nearby. In this regard, the usual practice is to draw the knife toward one's self when opening a box, and an overdraw of the knife could seriously cut the user once the blade clears the end of the box. Indeed, flesh cuts caused by overly aggressive and perhaps inattentive opening of paperboard boxes are not uncommon, particularly at retail stores.